Current methods to study proteins involved in epigenetic gene regulation mainly use isolated histone N- or C terminal tail peptides, full length histone dimers, tetramers or octamers from natural sources such as cells of animal, plant or fungal origin or from recombinant sources such as artificial overexpression in E.coli or other expression hosts or purified mono- or oligonucleosomes from tissue or cell culture. However, some of these histone subunits do not correspond to the physiological substrate of the epigenetic gene regulation enzymes. Others, such as purified mono- or oligonucleosomes have a heterogeneous post-translation modification pattern which does not allow for a robust and clear readout with respect to post-translational modifying enzyme function. So far, the provision of mono- and oligonucleosomes with a homogenous modification pattern in high yields has been a bottle-neck. Therefore, there is still a need for a sensitive, robust and/or scalable assay for determining the binding and/or functional interaction of post-translational modification proteins.